Those cars present the combination of high effort and low finished-project value that we look for in these parts, but let's face it: Pistons are too easy! What you need to struggle with now is a vehicle with Wankel aka rotary engine power from the early days of the technology, and we're not talking about a nice, easy RX-7 here.

Rotary engine inventor Felix Wankel was a card-carrying Nazi Party member and Obersturmbannführer in the SS, which will allow you to curse "that evil war criminal who thought up this stupid engine idea" as you're struggling with apex seals for the 29th consecutive hour.

In the 1950s, the Wankel engine was going to be The Next Big Thing in automotive power—such simplicity! Such smoothness! Such compactness! In reality, the path from engineering concept to production-car engine turned out to be nightmarishly difficult. Mazda and German automaker NSU persevered, and NSU was able to bring the Wankel-in-the-back Spider to market in 1964. The Spider wasn't exactly reliable, but NSU felt confident enough to follow it up in 1967 with a Wankelized luxury sedan, the Ro 80.

From a business standpoint, the Ro 80 (with its failure-prone apex seals and eccentric shaft bearings) was a disaster for NSU, enabling Audi to gobble up the tattered remnants of the company, and most examples got crushed long before the 1970s ended. That's a shame, because the combination of futuristic good looks and importance in automotive history makes the NSU Ro 80 a must-have for demented serious automotive aficionados.

Such a perfect Hell Garage candidate, but you're probably safe from the impossible-to-find Ro 80. Oh, hold on—not so impossible, it turns out, because we've found this 1967 Ro 80 in Pennsylvania. It's astoundingly a little bit rough, no getting around that, but the asking price is only $1,450.

According to the seller, this car "was used by the Curtis-Wright Co. to evaluate the rotary engine for use in Air Craft" and is "rough but appears complete." The engine is in a million tiny incomprehensible orphaned pieces and "will need a full rebuild," so you'll be guaranteed some world-traveling adventures tracking down NOS NSU rotary rebuild components. The car is "quite rusty" and the paint is "beyond buffing," so you'll need to hire a master body-and-paint man to fabricate all the unobtainium Ro 80 stuff that exists only as distant memories for elderly European junkyard proprietors. The good news: The crazy Sportomatic crypto-automatic transaxle is still there!

If the Ro80 isn't your choice, the Mazda REPU is the other Project Car Hell choice.

NSU was first to bring a fuel-chugging, unreliable Wankel-powered car to market, but Mazda was the company that never gave up on the rotary concept, no matter how many "devil's claw marks" appeared inside the rotor housings.

The impossibly beautiful Cosmo 110S hit the streets in 1967 . . . and started right away with the litany of Wankel problems that most Ro 80 owners could recite.

We tried to find a project Cosmo in the United States for a proper matchup with the Ro, but no dice (better still would have been a Citroën M35). The good news (for the Hell Garage Demons, not you) is that we were able to find a weird Wankel-motivated Mazda from the era before all the bugs were worked out of the engine: the Mazda REPU.

Why, you may ask, did only one company build a Wankel-powered pickup truck? We can't say, because other than the fact that pickups need big torque (which Wankels cannot produce) and owners of small pickups prize reliability (which the early Mazda Wankel didn't have) and fuel economy (the REPU sucked gas at about the same rate as the Chrysler Imperial), the REPU made perfect sense. Such a fine PCH candidate, and we've got this '74 Mazda REPU in Los Angeles (go here if the listing disappears) for just 50 bucks more than the Ro 80.

Naturally, such an amazing truck will need a complete and detail-obsessed restoration, which means ditching the shell and replacing the cut-out rear cab wall. The good news is that these trucks share a lot of components with easy-to-find Ford Couriers, and maybe sheet metal sliced from a Courier cab will work. It comes with a "5 speed cosmo trans" (which probably means an RX-5 transmission in this case), and you'll need to find the correct four-speed transmission; sure, you could just put a four-speed shift knob on it, but you'll know it's wrong. Rust? Probably not too bad, this truck is coming from SoCal. The wiring harness is guaranteed to have been thoroughly butchered over its lifetime, so you'll need to find an NOS factory harness (ho, ho!) or re-create your own at great expense. Totally worth it, we say!